An antibody is composed of a heavy chain (H chain) and a light chain (L chain). The heavy chain and light chain are composed of a variable region (VR) and a constant region (CR). The variable region has a complementarity-determining region (CDR). Further, the light chains of the antibody are classified into κ-type light chains and λ-type light chains.
In recent years, an antibody having enzyme-like activity, that is, an abzyme, has attracted considerable attention. Such an abzyme is expected to be used in many fields, such as the medical field, and chemical and food industries, because it has both high molecular recognition ability and enzymatic activity of an antibody. In particular, an abzyme having high specificity to a target molecule and which is capable of exhibiting cytotoxicity against the target molecule by enzymatic activity is expected to be used as an effective anti-cancer drug having few side effects. Particularly, since a human abzyme is expected to cause few side effects when it is administered to the human body, domestic and foreign pharmaceutical companies have been waiting for the development of useful human abzymes.
The present inventors have carried out various types of original research relating to abzymes (for example, refer to PTL 1). Among them, in PTL 2, an abzyme composed of a human antibody κ type light chain having antiviral activity against rabies virus or influenza virus has been reported.